Method of regulating alternating-current motors.



PATENTED JAN. 1, 1907. W.

B. G. LAMME & 0. RENSHA METHOD OF REGULATING ALTERNATING CURRENT MOTORS.

APPLICATION FILED IEB.6, 1905.

4 SHEBTS-SHEET l.

, I VENTORS WITNESSES:

7? M @h'o 6. 6M.

kTTORNEY N0. 840,001. PATENTED JAN. 1, 1907.

B. G. LAMMB & 0. RENSHAW. METHOD OF REGULATING ALTERNATING CURRENT MOTORS.

APPLIGATION- FILED FEB. 6. 1906.

- 4 SHEETS-SHEET 2. T 4

11 L I T 'l E W M WITNESSES: I VENTORS QJ JAM um W M ATTORNEY No. 840,001. 1 PATENTED-JAN. 1, 1907.

B. G. LAMME & 0. RENSHAW.

METHOD OF REGULATING ALTERNATING CURRENT MOTORS.

APPLICATION FILED FEB. 6, 1905.

4 SHBETSSHEET 3.

WITNESSES:

. INENTORS 747% 040 6.6% v ATTORNEY B. G. LAMME & O. RENSHAW.

METHOD OF RBGULATING ALTERNATING CURRENT MOTORS. APPLICATION FILED FEB. a, 1905.

PATENTED JAN. 1, 1907.

4 SHEETS-SHBET 4.

29 L 28 L 27 Z6 3 0 Fig. 5.

L 9 g C D a WITNESSES: I VENTORS ATTOHNEY UNITED sTATEs PAZEN T OFFICE.

BENJAMIN G. LAMME, OF PITTSBURG, AND CLARENCE RENSHAW, OF

WILKINSBURG, PENNSYLVANIA, ELECTRIC & MANUFACTURING PENNSYLVANIA.

ASSIGNORS TO WESTINGHOUSE COMPANY, A CORPORATION OF METHOD OF 'REGULATING ALTERNATlNG-CURRENT MOTORS- Specification bf Letters Patent. Application filed February 6,1905. Serial No. 244.482.

- Patented Jan. 1, 1907.

To all hom it may concern:

Be it known that we, BENJAMIN G. ITAMME,

- residing at'Pittsburg, and CLARENCE REN- sHAw, residing at Wilkinsburg, in the county of Allegheny, State of Pennsylvania, citizens of the United States, have invented a new tator type of'construction; and its object is I to provide a-inethod of' adjusting the phase and useful Improvement in Methods of Regulating Alternating-Current Motors, of which the following is a specification.

Our invention relates to the regulation of alternating-current motors of the commurelations with respect to each other of the currents in the armature and field-magnet windings of a motor, which shall insure the operation of the motor with a minimum armature-current for a given torque, and conse uently at high efficiency and power factor. general motors of the commutator type of construction if properly designed may be operated efiiciently by means of alternating currents, provided the currents in the armature .and field-magnet windings reverse simultaneously, or nearly so. I

If the armature and field circuits of a motor of-the commutator typehaving laminated magnetic circuits are supplied with alternating electromotive forces differing ninety degreesin phase, the currentsinthe armature and field -magnet windings may reverse nearly simultaneously. This is true because the current supplied to the field-magnet little in phase.

winding may be largely a magnetizing or wattle'ss current which lags nearly ninety degrees behind the electromotive force impressed upon, that circuit, while the arma-' turecircuit may be and is ordinarily made with but little seIf induction, so thatthe current in this circuit lags but little behind the electromotive force impressed upon it. It is obvious, then, that if the electrome- .tive forces applied to the two circuits dif fer ninety degrees in phase the currents in the armature and field-magnet circuits differ but It has been found in practice, however, that in order to obtain minimum armature-current for a "given torque with such a motor it is necessary that the currents in the armature and field circuits be more nearly coincidentin phase than. is

the case if j only the diflere'nces of the power factors of the circuits are depended upon to produce'the proper relations. The insufficiency of the power-factor conditions of the circuits is partially due to the fact that the I armature-circuits cannot be made entirely 1 non-inductive. Moreover, when constant voltages are applied to the armature and field-magnet windings the amount of current in the field-magnet winding, as well as its phase relation with respect to the electro-. motive force applied to the winding, remains practically constant even under variations in theload upon the motor; but the amount of current in the armature-circuit varies according to the work which the motor is doin and the phase relations of this current wit respect to the electromotive force applied to the armature-winding varies as the amount of current varies. Thus the phase relations of the currents in the armature and field magnet windings with'respect to each other vary as the work done by the motor. With no load on the motort. a, with but small currents flowing in the armature-circuit the phase relations may be reasonably close to the desired relations; but as load is placed on the motor the phase relations with respect 'to each otherof the armature and field currents change. I

It is the purpose of this invention to provide a method of effecting the proper ad uStment of the phase relations of the armature and field currents in order to obtain minimum armature-current for a given torque regardless of the load upon the motor.

, of the approximate phase relations as theyoccur in the modification shown in 5. Fig. 8 illustrates diagrammatically a motor which is supplied from a threehase source roe and which is also provided wit means for effecting changes in the phase relations of the currents in the armature and field cir cuits; and Figs. 9 and 10 are vector diagrams, illustrating the approximate phasetor 2, having a closed-coil armature-winding through conductors 3 and 4. Armature 5 of motor 6 derives its energy from the transformer-winding 1, a suitable means for varying the electromotive force applied to the armature-winding comprising a pivoted arm 7, adapted to engage contact-terminals 8, which are connected to spaced points in the transformer-winding 1 by means of leads 9.

Oneterminal of the field-magnet winding 10 of the motor 6 is connected to supply-conductor 11 and the other terminal is connected to a suitable conducting-strip 12 of a regulating device 13. A brush 14 is adapted to make sliding contact with the conductingstrip 12 and to engage contact-terminals 15, which are connected with suitable spaced 7 points in a winding 16, which is placed in the nected to supply-conductor 17.

same magnetic circuit as the transformerwinding 1 and one terminal of which is con- The brush 14 is carried by the magnetizable core 18 of a solenoid'20, which is connected in series with the motor-armature. A spring 21 is attached to-thebrush 14 in any suitable manner-for the purpose of resisting the pull ex.- ertedby the solenoid 20. If the current in the armature-circuit increases, the brush 14 is moved so as to cut into the field-circuit more of the winding 16, and-if, the current in the armature-circuit"decreases the spring 21 causes part of thewinding 16to be-cut out of the field-circuit. 1 It is of course understood that the controlling device 13 is illustrative of any suitable means for varying the length of the winding 16 included in thefield-circnit substantially inaccordance lwith variations in. the

amount of currentin the armature-circuit and that other devices for'efieeting this result may be employed within the scope of.

our invention.

An understanding of. the approximate phase relations of the currents and electro: motive forces in thearmature and fieldemagnet windings under the different conditions may beobtained from a consideration of Figs. 2 and 3. In Fig. 2 we have shown the phase relations as they would occur in the motor if no auxiliar I devices-were employed for altering them. lines OE and OEfrepresent, respectively, the electromotive forces applied to the armature and. field-magnet windings, and lines OI and OL represent in direction the currents in the armature and field-magnet windings. The angle 6) representsthe phase difierence between the ourthe electromotive force 00 that is derived from the Winding 16', the electromotive force ()0 being in phase with the electromotive force OE I The angle E OI is determined by the power factor ofthe field-circuit and remains the same in both cases. As above noted, the angle E,-OE in Fig. 3 is less than the corresponding angle. inFigf 2, and hence the angle Gin Fig. 3.is'less than the angle 9 in Fig. 2. The field magnetism being proportional to and in phase with the field-current,

the line OI may represent the phase direction of the field magnetism as well as that of r the field-current.

The torque exerted. by the armature of SIICh' a motor as is hereinbefore described is pro.

portional to the roduct of the armaturecurrent 01 and t at component OD-of the field magnetism which is in phase with the armature-current. -It. is evident that when the angle 6 is a minimum the component OD is a maximum and whenthe component OD is a maXimum'i. 6., when the field andarmature currents are most nearly in phase the power-factor of the motor is a maximum and the armature-current a minimum for that particular torque. It will be understood that the electromotive force represented by the line OCmay be chosen of such magnitude that the resultant electromotive force OE, and the correspond=-' ing' current OI, may be shifted to bring the field-magnet. currentOI and the armaturecurrent 01 into phase with each so'that the lines 0L and 01,, will coincide in. direction. While this-isa desirable condition for operation and, as just stated, may be attained if the component forces are roperly chosen, we have indicated relations t at only approximate this condition, for the reason t at such approximation may be more con? veniently and clearly illustrated. 1

Various modifications of our invention, such as are shown in Figs. 4, 5', and'7, may be found of use in special cases, though in general they are not so economical in construction. In Fig. 4- the winding 16 is-the s'econdary winding of a separate transformer 21*, the primary winding 22 of which is connected-v between the same supply-conductors 3 and*4 as the transformer-Winding 1.

The approximate phase relations. of the otheri. 6.,

IIS

currents and electromotive forces in the armature and field-magnet windings embodied in the system shown in Fig. 4 are substantially the same as in Fig. 3.

In Fig. '5 the winding 16 of an autotransformer 23 is connected 'to supply-conductors 4 and 17, the electromotive force between' which differs in phase from that, applied to the armature-circuits and also from that applied to the field-magnet'circuit. The approximate phase relations are shown in Fig. ,6, in which the electromotive force OE impressed upon the field-magnet winding is the ..'resultant of the electromotive force OE,

applied to the field-circuit and the electromotive force derived from the winding '16.

An autotransformer winding 24 may-also be connected between the same supply-conductors 3 and 4 as is the main transformerwinding 1, and the points of connection of the field-magnet winding therewith maybe shifted in accordance with Variations .in the amount of current traversing thearmatnre' circuit, substantially as shown in Fig. 7.

plied with one phase of the energy from a three-phase source 26 through supply-conductors 27 and 28, and, as before, the armature 5 of motor 6 derives its energy from the transformer-winding. I One terminal of the field-magnet winding 10 is connectedto the third supply-conductor 2'9 and the other terminal to the conducting-strip 12 of 'a regulator device 13, the details of which are similar to those shown in Fig. 1 and need not be further described. The contact-terminals 15, however,.'of the regulating device 13 are onnected with points in the transformerwinding near its middle, and the phase relations of the electromotive forces applied tothe armature and field-magnet windings are varied substantially in accordance with variatlons 1n the amount of current travers-- ing the armature-circuit by the automatic variation of the osition of the brush 14.

The same re e'rence characters are employed in Fig. 9 as in the revious figures for designating the phase re ations of the ourrents and electromotive forces in the armature and field-magnet windings, and these phase relations are illustrated as they occur when the terminal of the field-magnet winding 10 is connected to the middle point of the transformer-winding 25.

Fig. 10 shows'the phase'relations of the currents and electromotive forces in the armature and field circuits as they are altered by'a change in the position of the brush 14, it being observed that the angle 6 is less in Fig. 10 than in- Fig. 9.

While we have shown and described our invention as employed onl for the purpose of altering the phase of t e current in the field-magnet winding with'respect to that of the current the armature-winding, it is of v In-Fig. 8 a transformer-winding 25 is supcourse understood that if it is desired so to do the phase" of the current in the armature-f winding with respect to that of the current in the field-magnet winding may be adjusted in accordance with the same method and to meet the same or-any other desired conditions. p

Specific means for efiecting adjustment of the phase relations of the currents in the ar- .matur e and field-magnet windings form the subjects-matter of applications, Serial Nos.

244,475 and 244,476, filed b Benjamin G. Lamme, and of an application, Serial No. 244,481, filed by Clarence Renshaw, all of even date herewith.

. We claim as our invention 1. The method of maintaining approximately constantphase relations between the currents in two circuits, which consists in'varying the phase relations of the applied electromotive forces approximately in accordance with the variations in the amount of current traversin one of the circuits;

2. The metho of maintaining approximately constant phase relations between the currents in two circuits, which consists in combining with the electromotive force applied to "one of the circuits an out-of-phase electromotive force .and in varying the amount of said electromotive force approximately in accordance with the variations in the amount of current traversing one of the circuits.-

3. The-method of varying the phase relations of currents in different circuits, which consists in varying the phase relations of the electromotive forces applied to those circuits, substantially in accordance with variations in the phase difference between the current and electromotive force of the circuits.

4. The method of varying the phase relations of currents in different circuits, which consists in varying the phase relations of the electromotive forces applied to those circuits by combinin 'with one of the electromotive forces an ad itional electromotive force of a different phase, and in varying the same substantially in accordance with variations in the phase difference between the current and electromotiveforce of the other circuit.

5. The method of varying the phase relahase difference between ;he amount of current that "traverses the.

)ther winding.

7. The method 'of'adjusting thephase diference between the currents in the armature LHd field-magnet windings of va dynamo-elecric -machine which iluralit of out-of-phase electromotive forces the circuit of the field-magnet winding and a varying one of the electromotive forces ubstantially in accordance with Variations 1 the amount of current that traverses the rmature-Winding.

8. The method of adjusting the phase difsrence'between'the currents in the armature [1d field-magnet windings of a dynamoeelec- 'ic machine which consists in applying a lurality of out-of-phase electromotiv'e forces v the circuit of one of the windings and in iryin one of the electromotive forces subantia ly in accordance with variations in re phase difference between the current and ectromotive force of the other winding.

consists in applying a 9 The method of OUITBH 1n the armature and field-inagn'etwindings 0 a dynamo-electric machinewhioh consists in Varying the phase relations of the electromotive forces applied to those" windings, substantially in accordance with variations in. the amount of current that traverses thearmature-Winding.

10. The method of adjusting the phasedifference between the currents in the armature and field-magnet windings of a dynamo-electric machinevwhich' consists in varying the,

phase relations of the electromotive forces applied to those'windings, substantially in accordance with variations in the hase difference between the current and e tive force of one of the windin In testimony whereof we gave. hereunto subscribed our names this 3d day of February, 1905.

BENJ. G LAMME. CLARENCE RENSHAW.. Witnesses:

.OTTo S. SCHAIRER,

BIRNEY HINES.

ctromo 

